S
M
T
W
T
F
S
26
58°
31°
27
66°
35°
28
57°
49°
29
52°
41°
30
53°
41°
1
47°
32°
2
47°
28°
3
52°
43°
4
60°
47°
5
58°
37°
6
51°
35°
7
50°
35°
8
49°
35°
9
50°
37°
10
53°
40°
11
56°
39°
12
55°
40°
13
57°
41°
14
56°
40°
15
58°
38°
16
58°
41°
17
59°
42°
18
59°
48°
19
64°
47°
20
65°
47°
21
66°
48°
22
65°
43°
23
61°
47°
24
65°
42°
25
60°
40°
26
61°
47°
27
61°
49°
28
70°
50°
29
66°
47°
30
63°
44°
31
63°
41°
1
62°
42°
2
61°
42°
3
63°
43°
4
63°
44°
5
64°
46°
6
63°
46°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Janetville
Janetville's May 2026 forecast shows daily high temperatures ranging from 47° to 70°, with overnight lows between 28° and 50°. The average high for May is 59° with an average low of 42°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how May weather will actually feel in Janetville. See also: June | July | August.